latitude e5450 no post

i have an e5450 that does not post.  when I push the power button, i get power light, then the fan for 5 seconds then fant stops, then goes immediately to: power light off, hard drive and wireless lights on steady, and blinking battery light (screen stays completely black; no text or splash screen). if I press the power button again, it goes right back to power light on steady, fan for 5 seconds then power light off, hard drive and wireless on steady, and blinking battery light. I have looked through the manual and cannot find this scenario of blink codes. i have tried several different memory modules that are known good working modules. i have disconnected the drive. I'm really at a loss and am hoping someone can shed some light on this.  greatly appreciate any help.  thanks!